Why NaruSaku is referred to Heaven and EarthHeaven and Earth refers to two different scenes in the manga.More Like This
Before Team 7 heads off to the preliminary rounds, they open the "Heaven and Earth" scrolls in which summons Iruka, congratulating them on their advance. Before they go off, they ask about the scroll on the wall and Iruka explains, refering Naruto to Earth and Sakura to Heaven.
As said in the anime:
(thank you harunoanduzumaki
"If heavenly qualities are your desire
aquire wisdom; take your mind higher.
if earthly qualities are what you lack,
train your body; prepare to attack.
when heaven and earth are opened together
the perilous path will become riteous forever."
-Iruka (anime version)